Private branch exchange

ABSTRACT

When an exchange detects that a wireless base station is connected to an extension interface, the exchange outputs a sync signal to a communication channel of the extension interface. Based on the sync signal received through the communication channel, the wireless base station outputs a radio signal so as to communicate with a wireless handset based on the sync signal.

TECHNICAL FIELD

The present invention relates to an exchange to which a wireless basestation capable of communicating with a plurality of wireless handsetscan be connected.

BACKGROUND ART

There has been heretofore an exchange to which a wireless base stationis connected so that the exchange can communicate with a plurality ofwireless handsets through the wireless base station. Such an exchangehas a dedicated interface through which the wireless base station isconnected to the exchange. The exchange is designed so that the exchangecan communicate with the wireless handsets by connection of the wirelessbase station to this dedicated interface (for example, see PatentDocument 1).

Patent Document: Japanese Patent Publication No. JP-A-8-130757/(1996)

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve

In the background-art configuration, however, the dedicated interface isrequired for operating the wireless base station, whereby the exchangecomes high in cost for a user thereof

In addition, when only a dedicated interface having I/Fs to which aplurality of wireless base stations can be connected is provided, thededicated interface has to be purchased for connecting or adding onlyone wireless base station. Thus, the unused I/Fs are wasteful.

It is therefore an object of the present invention to provide anexchange which can operate a wireless base station without any interfacededicated to the wireless base station.

Means for Solving the Problems

The present invention provides a private branch exchange including: anextension interface capable of communicating with an extension telephoneor a wireless base station; a time division switch forconnecting/disconnecting channels; a memory for storing at least one ofsetting information and a program; a clock generator for generating async signal for the aforementioned wireless base station; and a CPU forcontrolling the private branch exchange as a whole; the private branchexchange being characterized in that:

the aforementioned extension interface includes a feeder for feedingpredetermined power to the aforementioned extension telephone or theaforementioned wireless base station, and a detector for detecting thekind of the aforementioned extension telephone or the aforementionedwireless base station; and

when the aforementioned detector detects the aforementioned wirelessbase station based on a response received by the aforementionedextension interface within a predetermined feeding period after power issupplied from the aforementioned feeder, the aforementioned detectorfurther detects the kind of the aforementioned wireless base stationbased on a response received by the aforementioned extension interfaceto an enquiry transmitted by the aforementioned extension interface.

Effect of the Invention

When an exchange according to the present invention detects that awireless base station is connected to an extension interface, theexchange outputs a sync signal to a communication channel of theextension interface. Based on the sync signal received through thecommunication channel, the wireless base station outputs a radio signalso as to communicate with a wireless handset based on the sync signal.Thus, the private branch exchange according to the present invention hasan advantage that a wireless base station can be operated without anyinterface dedicated to the wireless base station.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] A configuration diagram of a private branch exchange systemaccording to Embodiment 1 of the present invention.

[FIG. 2] A configuration diagram of an extension interface in FIG. 1.

[FIG. 3] A diagram for explaining the operation of a detector in FIG. 2.

[FIG. 4] A configuration diagram of a wireless base station in FIG. 1.

[FIG. 5] A diagram for explaining slot timing of sync signals.

[FIG. 6] A diagram for explaining a data format.

[FIG. 7] A diagram for explaining the functions of the sync signals.

[FIG. 8] An operation flow chart of the private branch exchangeaccording to Embodiment 1 of the present invention.

[FIG. 9] An operation flow chart of the wireless base station accordingto Embodiment 1 of the present invention.

[FIG. 10] An operation flow chart of the wireless base station accordingto Embodiment 1 of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

1 private branch exchange; 2 a,b extension telephone;

3 a,b wireless base station; 4 a,b,c wireless handset;

11 a,b line interface circuit;

12 a-d extension interface circuit;

13 time division switch; 14 memory;

15 CPU; 16 clock generator;

17 communication I/F circuit; 18 driver receiver circuit;

19 transformer; 21 detector;

22 feeder; 31 transformer;

32 driver receiver circuit; 33 communication I/F circuit;

34 RF circuit; 35 baseband IC;

36 base station CPU; 37 base station memory;

38 indicator

Best Mode for Carrying Out the Invention

In order to solve the foregoing problems, the present invention providesa private branch exchange including: an extension interface capable ofcommunicating with an extension telephone or a wireless base station; atime division switch for connecting/disconnecting channels; a memory forstoring at least one of setting information and a program; a clockgenerator for generating a sync signal for the wireless base station;and a CPU for controlling the private branch exchange as a whole; theprivate branch exchange being characterized in that:

the extension interface includes a feeder for feeding predeterminedpower to the extension telephone or the wireless base station, and adetector for detecting the kind of the extension telephone or thewireless base station; and

when the detector detects the wireless base station based on a responsereceived by the extension interface within a predetermined feedingperiod after power is supplied from the feeder, the detector furtherdetermines whether the wireless base station is a 2.4 GHz wireless basestation or a DECT wireless base station, based on a response received bythe extension interface to an enquiry transmitted by the extensioninterface. The private branch exchange can operate the wireless basestation without any interface dedicated to the wireless base station.

In order to solve the foregoing problems, according to another aspect ofthe present invention, the present invention provides a private branchexchange system including: an extension interface capable ofcommunicating with an extension telephone or a wireless base station; atime division switch for connecting/disconnecting channels; a memory forstoring at least one of setting information and a program; a clockgenerator for generating a sync signal for the wireless base station;and a CPU for controlling the private branch exchange as a whole; theprivate branch exchange system being characterized in that:

the extension interface includes a feeder for feeding predeterminedpower to the extension telephone or the wireless base station, and adetector for detecting the kind of the extension telephone or thewireless base station; and

the detector determines which is connected, the extension telephone orthe wireless base station, based on a response received by the extensioninterface within a predetermined feeding period after power is suppliedfrom the feeder, and when the detector detects the wireless basestation, the extension interface communicates with the wireless basestation, and the detector determines whether the wireless base stationis a 2.4 GHz wireless base station or a DECT wireless base station,based on a response of the wireless base station to an enquirytransmitted by the extension interface. Even an exchange allowingconnection of a telephone to an extension interface circuit can bechanged so that a wireless base station can be connected thereto easily.

(Embodiment 1)

An embodiment of the present invention will be described below withreference to the drawings.

FIG. 1 is a configuration diagram of an exchange system according toEmbodiment 1 of the present invention, which is constituted by anprivate branch exchange 1, extension telephones 2, wireless basestations 3 and wireless handsets 4.

First, the configuration of the private branch exchange 1 will bedescribed. The private branch exchange 1 has line interfaces 11,extension interfaces 12, a time division switch 13, a memory 14, a CPU15 and a clock generator 16 as shown in FIG. 1.

The line interfaces 11 a and 11 b are line interfaces to which ISDNlines, analog lines, etc. from an office exchange can be connected. Eachline interface 11 a, 11 b has functions such as detection of an incomingcall from such an external line, response to the incoming call,acquisition or dial signal delivery for an outgoing call to the externalline, etc.

The time division switch 13 is a switch which can connect/disconnectchannels between the extension interfaces 12 and between the extensioninterfaces 12 and the external line interfaces 11. The time divisionswitch 13 has a channel memory and a peripheral control circuit forcontrolling the address of the channel memory in accordance with a timeslot, in the same manner as a general time division switch for use in adigital exchange system. These channel memory and peripheral controlcircuit are integrated into a large-scale integrated circuit (LSI), andprovided as one general-purpose IC, in the same manner as in the generaltime division switch. Incidentally, a laid-open publication (JapanesePatent Laid-Open No. 2000-333279) is used for reference by way ofexample, and detailed description about the contents of operation of thetime division switch 13 will be omitted.

The memory 14 stores various setting information or programs. Forexample, an SRAM (Static Random Access Memory) having a capacity of 1Mbyte is used with battery backup so as to store various settinginformation. A DRAM (Dynamic Random Access Memory) having a capacity of16 Mbytes is used as a work memory for processing. Further, a cardmemory having a capacity of 32 Mbytes is used for storing programs. Theaforementioned memory configuration is an example of a minimal systemconfiguration. The capacities will be increased in accordance with thefunctions of the private branch exchange. The embodiment of the presentinvention will be described below with those memories genericallyreferred to as the memory 14.

The CPU 15 controls the private branch exchange 1. A general-purposeone-chip CPU is used.

The clock generator 16 is a general-purpose programmable clock generatorIC for generating four kinds of sync signals. First, a sync signal(referred to as a first sync signal) for 2.4 GHz FHSS wireless basestations (referred to as first wireless base stations) and a sync signal(referred to as a second sync signal) for TDMA/TDD system DECT wirelessbase stations (referred to as second wireless base stations) aregenerated individually. Further, a sync signal for extension interfaces12 connected to the first wireless base stations and a sync signal forextension interfaces 12 connected to the second wireless base stationsare generated individually. Thus, the four kinds of sync signals aregenerated respectively.

Each extension interface 12 a-12 d has a function of communicating witha terminal device such as an extension telephone 2, a wireless basestation 3, or the like, so as to transmit/receive a control signal forcontrolling the terminal device or transmit/receive an audio signal.FIG. 2 is a configuration diagram of an extension interface circuitshown in FIG. 1. In FIG. 2, this extension interface circuit 12 has acommunication I/F circuit 17 for making communication with the CPU 15, adriver 18, and an impedance matching transformer 19 for makingcommunication with an extension telephone 2 or a wireless base station3.

A detector 21 has a function of detecting the kind of a terminalconnected to the extension interface circuit 12. For example, thedetector 21 has a function of determining whether the terminal is anextension telephone 2 or a wireless base station 3 and furtherdetermining whether it is for 2.4 GHz or for DECT if the terminal is awireless base station 3. The detector 21 has a basic configuration inwhich a control channel having a below-mentioned data format is storedin a shift register and a bit sequence is checked by a selector. Thebasic configuration including relevant peripheral timing control signalsis integrated into a custom LSI.

A feeder 22 has a function of feeding predetermined power to a deviceconnected to a port of the extension interface circuit 12. A powersupply controls to supply the predetermined power in a constant period.A general-purpose programmable power supply IC is used for beforehandcontrolling the mode of a voltage to be supplied.

The manner of determination will be described with reference to FIG. 3.FIG. 3 is a diagram for explaining the operation of the detector in FIG.2. When an extension telephone 2 or a wireless base station 3 isconnected to the port of the extension interface 12, the extensiontelephone 2 or the wireless base station 3 is supplied with power fromthe feeder 22. At the same time, a control channel (e.g. C channel) witha below-mentioned data format is checked. When a response (firstresponse) is received within a predetermined feeding period, it isconfirmed that the connected device is a model (extension telephone 2 orwireless base station 3) corresponding to the voltage mode (S41).

Next, command/response communication with the wireless base station 3 isestablished using the control channel (e.g. C channel) with the dataformat. When the communication is established, an enquiry as to the modeof the wireless base station 3 is sent to the wireless base station 3,and whether the mode is a 2.4 GHz mode or a DECT mode is determinedbased on the result of a response (second response) (S42).

The CPU 15 is notified of the result of determination as to the mode ofthe base station. After that, of the sync signals supplied from theclock generator 16, which time slot to use for exchanging theinformation of the wireless base station 3 is designated to theextension interface circuit 12 from the CPU 15. For example, the 2.4 GHzFHSS sync signal corresponds to Slot 1 on a time division highway (S43),and the DECT sync signal corresponds to Slot 2 on the time divisionhighway (S44).

Next, the configuration of the wireless base station 3 will be describedwith reference to FIG. 4. FIG. 4 is a configuration diagram of thewireless base station in FIG. 1. The wireless base station 3 has atransformer 31, a driver receiver circuit 32, a communication I/Fcircuit 33, an RF (Radio-Frequency) circuit 34, a baseband IC (BBIC) 35,a base station CPU 36, a base station memory 37 and an indicator 38.

The transformer 31 is a pulse transformer serving for impedance matchingwith the extension interface 12 in order to transmit/receive a frameoutput through the extension interface circuit 12.

The driver receiver circuit 32 is a circuit for amplifying a framesignal from the communication I/F 33 and for receiving a frame signaloutput from the extension interface 12 and transmitting the receivedframe signal to the communication I/F circuit 33.

The communication I/F circuit 33 is a circuit for transmitting/receivingaudio channels and first and second control channels. For example, anaudio channel signal transmitted from the extension interface 12 istransmitted to a wireless handset 4 through the BBIC 35 and the RF 34,and an audio signal received from the wireless handset 4 is transmittedto the extension interface 12 over an audio channel of a communicationframe. In addition, a signal on the second control channel transmittedfrom the extension interface 12 is output to the base station CPU 36,and a control signal output from the base station CPU 36 is transmittedto the extension interface 12 over the second control channel of thecommunication frame. Further, delay correction or the like is performedon a sync signal transmitted from the extension interface 12 through thefirst control channel, and the corrected sync signal is output to theBBIC 35, while a model code output from the base station CPU 36 istransmitted to the extension interface 12 through the first controlchannel.

The RF circuit 34 and the baseband IC 35 are wireless circuits formaking communication with the wireless handset 4 using an FHSS(Frequency Hopping Spread Spectrum) system, or a DECT system such asTDMA/TDD or the like.

Next, description will be made about the functions of the sync signalsfrom the clock generator 16 to the wireless base station 3. FIG. 5 is adiagram for explaining the slot timing of the sync signals. The clockgenerator 16 generates a 2.4 GHz FHSS sync signal and a DECT syncsignal. These two sync signals are supplied to the extension interfacecircuit 12 through the time division switch 13 over different slots ofone time division highway

For example, the 2.4 GHz FHSS sync signal is put on Slot 1 of the timedivision highway at intervals of 160 msec as a bit sequence of 74H. Onthe other hand, the DECT sync signal is put on Slot 2 of the timedivision highway at intervals of 2.4 sec as a bit sequence of 74H, andoutput to the time division switch 13.

FIG. 6 is a diagram for explaining a data format, which has a dataformat configuration composed of two audio channels (B1 and B2), a firstcontrol channel (Cch) and a second control channel (Dch). Each extensioninterface 12 can make communication with an extension telephone 2 or awireless base station 3 using such a data format. Incidentally, thisdata format is applied to both the transmission frame to be output fromthe extension interface 12 and the reception frame to be input to theextension interface 12.

Further, description will be made about the functions of the syncsignals among devices. FIG. 7 is a diagram for explaining the functionsof the sync signals. First, assume that a wireless base station 3 isconnected to the port of the extension interface circuit 12. The feeder22 supplies power of a voltage programmed in advance. At the same time,the CPU 15 is notified of the connection of the terminal.

The connected wireless base station 3 is supplied with the power. Thewireless base station 3 having begun to operate transmits its own modelcode to the extension interface circuit 12 over a control channel withthe data format. For example, the wireless base station 3 frames asignal over the first control channel (Cch) sequentially. When thewireless base station 3 is a 2.4 GHz FHSS wireless base station, thewireless base station 3 transmits a code of the 2.4 GHz FHSS wirelessbase station, and when the wireless base station 3 is a DECT wirelessbase station, the wireless base station 3 transmits another code (secondresponse).

The model code is interpreted by the detector 21 of the extensioninterface circuit 12. The detector 21 frames and reproduces the modelcode over the first control channel (Cch). The detector 21 detects themodel of the connected wireless base station 3 based on the model code,and notifies the CPU 15 of the detected model.

Based on the result of the model detection, the CPU 15 recognizes themodel of the wireless base station 3 connected newly. The CPU 15controls the time division switch 13 and the clock generator 16 so as tosupply a bit sequence of 74H to the extension interface circuit 12 overa slot of the time division highway. The CPU 15 arranges 8-bit data ascontrol data required for the 2.4 GHz FHSS wireless base station or theDECT wireless base station in accordance with the result of the modelrecognition, and transmits the 8-bit data to the extension interfacecircuit 12 over the time division highway with a bit sequence of 74H asone frame.

The extension interface circuit 12 importing the 8-bit data sequentiallyreconstructs the data into a data format of 2B+D (first control channelC) and transmits the reconstructed data to the wireless base station 3.

The wireless base station 3 frames the signal of the first controlchannel (C) sequentially so as to reproduce the 8-bit data andreconstruct the 8-bit data as its own control data. Examples of thecontrol data include movement data or control conditions of the wirelesshandset 4 or update data of the wireless base station 3 itselfFurthermore, the wireless base station 3 may additionally provide anidentification code (abbreviated to ID code) for identifying thewireless base station 3 itself together with the aforementioned modelcode of the wireless base station 3 itself to be transmitted at thebeginning of operation. Due to the ID code, it is possible to set optionfunctions peculiar to a system user or communication control conditionspeculiar to a call region of the wireless base station 3. These optionsor communication control conditions are transmitted from the privatebranch exchange 1 to the wireless base station 3 through the extensioninterface circuit 12 as the aforementioned update data of the wirelessbase station 3 itself.

Description has been made above using an example in which a bit sequenceof 74H is used in a time division highway, an example in which a signalon the first control channel (Cch) is used, and an example in which a2.4 GHz FHSS wireless base station or a DECT wireless base station isused as the wireless base station 3. However, the present invention isnot to be interpreted exclusively to such a bit sequence, such achannel, such a radio frequency or such a communication system. Not tosay, the present invention can use another hexadecimal code than the bitsequence, and the contents of the present invention can be applied toanother frequency, another channel or another communication system. Thesame thing can be also applied to the overall operation which will bedescribed below.

The operation of the private branch exchange in the private branchexchange system configured thus will be described below specificallywith reference to the flow chart of FIG. 8.

The CPU 15 of the private branch exchange 1 monitors the C channel inthe extension interface 12, and determines whether a model code of anextension telephone 2 or a model code of a wireless base station 3 hasbeen sent to the C channel or not (S1). When the CPU 15 concludes that amodel code of an extension telephone 2 has been sent, the CPU 15 refersto the memory 14 and determines whether this extension telephone 2 hasbeen set or not. When the CPU 15 concludes that the extension telephone2 has not been set yet, the CPU 15 extracts a default value for theextension telephone from the memory 14, and sets the extension telephonein the memory 14 so as to associate the extension telephone with theextension interface 12 where the model code was determined (S2).

On the other hand, when the CPU 15 concludes that a model code of awireless base station 3 has been received, the CPU 15 determines whethercommunication with this wireless base station 3 can be established ornot (S3). Whether the wireless base station 3 has been connected to theextension interface 12 or not is determined as follows. That is, arequest signal for communication establishment is received from thefirst control channel or the second control channel, and it isdetermined whether a predetermined exchange could be performed or not.Incidentally, this determination is made for each extension interface12. In such a manner, the CPU 15 establishes the communication with thewireless base station 3 by the predetermined exchange for communicationestablishment.

When the model code received in the first control channel is a modelcode of a wireless base station and for 2.4 GHz, the CPU 15 concludesthat the device connected to the extension interface 12 is a 2.4 GHzwireless base station (S4). Incidentally, the configuration may beadapted as follows. That is, the model code received in the firstcontrol channel serves for identification as to whether the connecteddevice is an extension telephone 2 or a wireless base station 3. Asecond model code (indicating whether the wireless base station 3 is a2.4 GHz wireless base station or a DECT wireless base station)transmitted from the wireless base station 3 via the second controlchannel is received as soon as communication is established in the stepS3. When the code is a mode code of a 2.4 GHz wireless base station, itis concluded that the wireless base station 3 is a 2.4 GHz wireless basestation.

Next, the CPU 15 determines whether the number of active wireless basestations having been already connected to the extension interfaces 12exceeds a predetermined number (which will be, for example, describedbelow on the assumption that connections with up to four wireless basestations are permitted) or not, based on the number (set number) ofwireless base stations set in the memory 14 (S5). When the number ofactive wireless base stations 3 exceeds the predetermined number, theCPU 15 does not set the wireless base station connected to the extensioninterface 12 in the step SI, and transmits a notification(connection-refused notification), which indicates that connection hasbeen refused due to the limit of the number of wireless base stations,to the wireless base station 3 via the second control channel.Incidentally, the configuration may be adapted so that theconnection-refused notification is not transmitted and any notificationis not issued.

When the CPU 15 concludes in the step S5 that the number of activewireless base stations 3 does not exceed the predetermined number, theCPU 15 refers to the memory 14 and determines whether this wireless basestation 3 has been already set or not. When the CPU 15 concludes thatthe wireless base station 3 has not been set yet, the CPU 15 extracts adefault value of a 2.4 GHz wireless base station from the memory 14, andsets the wireless base station 3 in the memory 14 so as to associate thewireless base station 3 with the extension interface 12 where the modelcode was determined (S6). After that, the CPU 15 uses the second controlchannel and/or the audio channels so as to transmit a 2.4 GHz wirelessbase station program to the wireless base station 3 connected to theextension interface 12 (S7, download). Incidentally, the CPU 15 maytransmit the program only when a request to send the 2.4 GHz wirelessbase station program is received from the wireless base station 3through the second control channel. After the CPU 15 sends the programto the wireless base station 3 in such a manner, the CPU 15 sends arequest to restart to the wireless base station 3 through the secondcontrol channel. When the restart of the wireless base station 3 isterminated, the CPU 15 transmits a 2.4 GHz sync signal through the firstcontrol channel. The wireless base station 3 extracts a wireless syncsignal from the first control channel, and establishes synchronism ofits wireless portion based on this wireless sync signal.

On the other hand, when the CPU 15 concludes in the step S4 that themodel code received in the first control channel is a model code of awireless base station 3 and for DECT, the CPU 15 concludes that thedevice connected to the extension interface 12 is a DECT wireless basestation. Incidentally, the configuration may be adapted as follows. Thatis, the model code received in the first control channel serves foridentification as to whether the connected device is an extensiontelephone 2 or a wireless base station 3. A second model code(indicating whether the wireless base station 3 is a 2.4 GHz wirelessbase station or a DECT wireless base station) transmitted from thewireless base station 3 via the second control channel is received assoon as communication is established in the step S3. When the code is amode code of a DECT wireless base station, it is concluded that thewireless base station 3 is a DECT wireless base station.

Then, the CPU 15 determines whether the number of active wireless basestations 3 having been already connected to the extension interface 12exceeds a predetermined number (for example, four) or not, based on thenumber of wireless base stations 3 set in the memory 14 (S8). When thenumber of active wireless base stations 3 is equal to the predeterminednumber, the CPU 15 does not set the wireless base station 3 newlyconnected to the extension interface 12 in the step SI, and transmits anotification (connection-refused notification), which indicates thatconnection has been refused due to the limit of the number of wirelessbase stations 3, to the wireless base station 3 via the second controlchannel. Incidentally, the configuration may be adapted so that theconnection-refused notification is not transmitted and any notificationis not issued.

When the CPU 15 concludes in the step S8 that the number of activewireless base stations 3 does not exceed the predetermined number, theCPU 15 refers to the memory 14 and determines whether this wireless basestation 3 has been already set or not. When the CPU 15 concludes thatthe wireless base station 3 has not been set yet, the CPU 15 extracts adefault value of a DECT wireless base station from the memory 14, andsets the wireless base station 3 in the memory 14 so as to associate thewireless base station 3 with the extension interface 12 where the modelcode was determined (S9). After that, the CPU 15 uses the second controlchannel and/or the audio channels so as to transmit a DECT wireless basestation program to the wireless base station 3 connected to theextension interface 12 (S10, download). Incidentally, the CPU 15 maytransmits the program only when a request to send the DECT wireless basestation program is received from the wireless base station 3 through thesecond control channel. After the CPU 15 sends the program to thewireless base station 3 in such a manner, the CPU 15 sends a request torestart to the wireless base station 3 through the first controlchannel. When the restart of the wireless base station 3 is terminated,the CPU 15 transmits a DECT sync signal through the first controlchannel. The wireless base station 3 extracts a wireless sync signalfrom the first control channel, and establishes synchronism of itswireless portion based on this wireless sync signal.

When the setting of connection of the wireless base station 3 isterminated in such a manner, the CPU 15 sends an “operation startnotification” to the wireless base station 3. On and after that, theprivate branch exchange 1 and the wireless base station 3 exchangecontrol data via the second control channel and exchange audio signalsvia the audio channels.

In such a manner, the private branch exchange according to Embodiment 1of the present invention receives a model code from the wireless basestation 3 using the first control channel, whereby it can be concludedthat the device connected to the extension interface 12 is a wirelessbase station 3. In addition, once the wireless base station 3 has beenconnected to the extension interface 12, a sync signal is transmittedfrom the private branch exchange 1 to the wireless base station 3 viathe first control channel. Accordingly, the wireless base station 3 canuse this sync signal to synchronize a radio signal with a radio signalof another wireless base station 3 connected to another extensioninterface 12 so as to make communication therewith.

Next, the operation of each wireless base station will be described withreference to the flow chart of FIG. 9.

When power is applied to the wireless base station 3, the base stationCPU 36 determines whether the wireless base station 3 has been connectedto an extension interface 12 of the private branch exchange 1 or not(S11). Whether the wireless base station 3 has been connected to anextension interface 12 or not is determined based on detection of aframe transmitted from the extension interface 12 at predeterminedintervals.

When the base station CPU 36 concludes that the wireless base station 3has been connected to an extension interface 12, the base station CPU 36transmits a frame including a request signal for communicationestablishment to the extension interface 12 via the second controlchannel. In addition, a model code (for example, a model code indicatinga DECT system) stored in the base station memory 37 of the wireless basestation 3 is transmitted to the extension interface 12 over the firstcontrol channel of the communication frame (S12). Incidentally, theconfiguration may be adapted as follows. That is, the model codetransmitted over the first control channel is designed foridentification as to whether the connected device is an extensiontelephone 2 or a wireless base station 3. A second model code(indicating whether the wireless base station 3 is a 2.4 GHz wirelessbase station or a DECT wireless base station) transmitted from thewireless base station 3 via the second control channel is transmitted assoon as communication is established.

Next, the base station CPU 36 determines whether a link of wirelesscommunication with the private branch exchange 1 via the extensioninterface 12 has been established or not (S13). When the communicationlink has not been established, a link error is indicated on theindicator 38 (S14). Incidentally, in the case of the indicator 38, forexample, the link error is indicated by turning on a red light.

In the case where the communication link has been established in thestep S13, when a connection-refused notification is received from theprivate branch exchange 1 via the second control channel (S15), the basestation CPU 36 indicates a connection limit on the indicator 38.Incidentally, in the case of the indicator 38, for example, a connectionlimit error is indicated by blinking the red light.

When a connection-refused notification is not received in the step S15or when a connection-accepted notification is received in the step S15,the base station CPU 36 issues a request to send a program for awireless base station (S17). When the program cannot be receivednormally, a program reception error is indicated on the indicator 38(S18). Incidentally, in the case of the indicator 38, for example, theprogram reception error is indicated by blinking an orange light.

When the base station CPU 36 concludes in the step S18 that the programhas been received, the base station CPU 36 stores this program in a bootarea of the base station memory 37. After that, when a restart requestis received from the private branch exchange 1, the base station CPU 36begins a restart operation and activates the program stored in the bootarea (S20).

After that, the communication I/F circuit 33 receives a sync signal fromthe first control channel, and outputs a radio signal from the RFcircuit 34 so that communication with the wireless handset 4 can beestablished (S23). When the sync signal cannot be received, a syncsignal extraction error is indicated on the indicator 38 (S18).Incidentally, in the case of the indicator 38, for example, the syncsignal extraction error is indicated by blinking the orange light.

In the aforementioned embodiment, description has been made about theprivate branch exchange 1 to which a 2.4 GHz wireless base station and aDECT wireless base station can be connected simultaneously. However, theprivate branch exchange 1 can be designed to operate only one kind ofwireless base station of them. Such an operation will be described belowspecifically with reference to the flow chart of FIG. 10.

The operation of steps S30-S32 is similar to the aforementionedoperation of steps S1-S3. Therefore, description thereof will beomitted.

After the communication with the wireless base station 3 is establishedin the step S32, the CPU 15 determines whether the number of activewireless base stations 3 having been already connected to the extensioninterfaces 12 is at least one or not, based on the number of wirelessbase stations set in the memory 14 (S33). When the CPU 15 concludes thatthere is no active wireless base station 3, the CPU 15 determineswhether the wireless base station 3 connected to the extension interface12 is a 2.4 GHz wireless base station or a DECT wireless base station,based on the model code received in the step S31. The determinedcommunication system (2.4 GHz or DECT) of the wireless base station 3 isset in the memory 14 as a wireless communication system of the privatebranch exchange 1(S34).

On the other hand, when the CPU 15 concludes in the step S33 that thenumber of active wireless base stations 3 is at least one, the CPU 15determines whether the wireless base station 3 connected to theextension interface 12 is a 2.4 GHz wireless base station or a DECTwireless base station, based on the model code received in the step S31,and determines whether the determined communication system (2.4 GHz orDECT) of the wireless base station 3 is identical to the wirelesscommunication system of the private branch exchange 1 set in the memory14 or not (S35). As a result of determination, when the CPU 15 concludesthat the determined communication system is not identical to the setwireless communication system, the CPU 15 does not set the wireless basestation 3 connected to the extension interface 12, but transmits anotification (connection-refused notification), which indicates thecommunication system of the wireless base station is wrong, to thewireless base station 3 through the second control channel.Incidentally, the configuration may be adapted so that theconnection-refused notification is not transmitted and any notificationis not issued. Further, the operation on and after the step S37 may beperformed without determining the communication system (2.4 GHz or DECT)of the wireless base station 3 in the step S35.

After the operation of the step S34 is terminated or when it isconcluded in the step S35 that the determined communication system isidentical to the set wireless communication system, the CPU 15 transmitsvarious parameters to the wireless base station 3 through the secondcontrol channel.

Here, the parameters includes (1) a private branch exchange model code,(2) a base station number, (3) a C channel delay, (4) a PCM system mode,(5) a private branch exchange number, (6) an ADPCM/PCM selection, etc.

The private branch exchange model code is a code indicating the kind ofprivate branch exchange. The wireless base station 3 receiving this codechanges over the communication protocol between the extension interface12 and the wireless base station 4 so as to establish communication withthe extension interface 12. In such a manner, communication can beperformed with a proper protocol adapted to each private branch exchangeafter the communication is established.

The base station number is a unique number assigned to each wirelessbase station 3. The base station number is included in a radio signaloutput from each wireless base station 3 so as to allow each wirelesshandset 4 or the like to recognize the wireless base station 3. When thebase station CPU 36 of the wireless base station 3 receives a basestation number, the base station CPU 36 outputs a radio signal includingthe received base station number.

The C channel delay is calculated as a signal delay time between theextension interface 12 and the wireless base station 3 based on thetiming when a signal is output from the extension interface 12 and thetiming when the signal turns back from the wireless base station 3connected to the extension interface 12. The CPU 15 calculates the Cchannel delay. When the base station CPU 36 of the wireless base station3 receives the C channel delay from the extension interface 12, the basestation CPU 36 outputs a radio signal based on the received delay and async signal.

The PCM system mode indicates whether the PCM system of an audio digitalsignal exchanged through the B channel is A-law or μ-law. The basestation CPU 36 of the wireless base station 3 decides the PCM system inaccordance with the PCM system mode transmitted from the private branchexchange 1.

The private branch exchange number is a unique number assigned to eachprivate branch exchange. The private branch exchange number is includedin a radio signal output from each wireless base station 3 in order toallow each wireless handset 4 or the like to recognize the wireless basestation 3 when a plurality of private branch exchanges are provided.

The ADPCM/PCM selection indicates whether the PCM system of an audiodigital signal exchanged through the B channel is ADPCM (32 kbps) or PCM(64kbps). The base station CPU 36 of each wireless base station 3decides either ADPCM or PCM in accordance with information transmittedfrom the private branch exchange 1, and performs transmission/receptionover the B channel.

When the wireless base station 3 receives the parameters transmittedfrom the private branch exchange 1 in such a manner, the wireless basestation 3 changes over to a normal operation state (operation mode).

Incidentally, there is no description about transmission/reception ofparameters in the operation shown in the flow chart of FIG. 8 or FIG. 9.However, transmission/reception of parameters can be performed togetherwith transmission/reception of a program or in place oftransmission/reception of the program. On the other hand, there is nodescription about transmission/reception of a program or limitation ofthe number of wireless base stations in the flow chart of FIG. 10. Notto say, however, transmission/reception of a program or limitation ofthe number of wireless base stations can be performed as described inthe flow chart of FIG. 8.

In addition, in Embodiment 1 of the present invention, a sync signal isoutput from the private branch exchange 1 after a predeterminedoperation is performed between the private branch exchange 1 and eachwireless base station 3. However, when there is only one kind ofwireless base station 3 (for example, only the DECT system), the syncsignal may be always output to the second control channel.

In addition, in Embodiment 1 of the present invention, a program for awireless base station is transmitted/received between the private branchexchange 1 and each wireless base station 3. However, the program can bestored in the wireless base station 3 in advance so that the programdoes not have to be transmitted/received.

In addition, in Embodiment 1 of the present invention, description hasbeen made on the assumption that a program for a 2.4 GHz wireless basestation and a program for a DECT wireless base station are providedseparately. However, one program may be shared between the two kinds ofwireless base stations. In addition, the kinds of wireless base stationsare not limited to the 2.4 GHz wireless base station and the DECTwireless base station. For example, the present invention can be alsoapplied to three or more kinds of wireless base stations including a9GHz-band wireless base station.

In addition, description has been made above on the assumption thatconnections of up to four wireless base stations are permitted. However,the number of connected wireless base stations is not limited to four,but another number of connected wireless base stations can be set inaccordance with the terminal reception capacity of the private branchexchange 1 (that is, the control capacity of the exchange).

Although the present invention has been described in detail and withreference to its specific embodiment, it is obvious to those skilled inthe art that various changes or modifications can be made on the presentinvention without departing from the spirit and scope thereofIncidentally, this application is based on Japanese Patent ApplicationNo. 2003-407231 filed on Dec. 5, 2003, and the contents thereof areincorporated herein by reference.

INDUSTRIAL APPLICABILITY

In an exchange to which a wireless base station capable of communicatingwith a plurality of wireless handsets can be connected, the wirelessbase station can be operated without any interface dedicated to thewireless base station.

1. A private branch exchange comprising: an extension interface capableof communicating with an extension telephone or a wireless base station;a time division switch for connecting/disconnecting channels; a memoryfor storing setting information and/or a program; a clock generator forgenerating a sync signal for said wireless base station; and a CPU forcontrolling said private branch exchange as a whole; wherein saidextension interface includes a feeder for feeding predetermined power tosaid extension telephone or said wireless base station, and a detectorfor detecting the kind of said extension telephone or said wireless basestation; and when said detector detects said wireless base station basedon a response received by said extension interface within apredetermined feeding period after power is supplied from said feeder,said detector further detects the kind of said wireless base stationbased on a response received by said extension interface to an enquirytransmitted by said extension interface.
 2. A private branch exchangeaccording to claim 1, wherein said CPU designates a time slot of saidsync signal to be supplied from said clock generator to said extensioninterface through said time division switch as said time slotcorresponding to the kind of said wireless base station for saidextension interface based on a result of detection of said detector. 3.A private branch exchange system comprising: an extension interfacecapable of communicating with an extension telephone or a wireless basestation; a time division switch for connecting/disconnecting channels; amemory for storing setting information and/or a program; a clockgenerator for generating a sync signal for said wireless base station;and a CPU for controlling said private branch exchange as a whole;wherein said extension interface includes a feeder for feedingpredetermined power to said extension telephone or said wireless basestation, and a detector for detecting the kind of said extensiontelephone or said wireless base station; said detector detects saidextension telephone or said wireless base station based on a responsereceived by said extension interface within a predetermined feedingperiod after power is supplied from said feeder; and when said detectordetects said wireless base station, said extension interfacecommunicates with said wireless base station, and said detector detectsthe kind of said wireless base station based on a response of saidwireless base station to an enquiry transmitted by said extensioninterface.
 4. A private branch exchange system according to claim 3,wherein said CPU designates a time slot of said sync signal to besupplied from said clock generator to said extension interface throughsaid time division switch as said time slot corresponding to the kind ofsaid wireless base station for said extension interface based on aresult of detection of said detector.
 5. A private branch exchangesystem according to claim 3, wherein said CPU transmits a program forsaid wireless base station corresponding to said detected kind based onsaid detection of the kind of said wireless base station.
 6. A privatebranch exchange system according to claim 3, wherein a plurality ofextension interfaces including said extension interface are provided,and said CPU sets the number (set number) of said wireless base stationsconnectable to said extension interfaces in advance so as not to set anumber of said wireless base stations beyond said set number.
 7. Aprivate branch exchange system according to claim 3, wherein a pluralityof extension interfaces including said extension interface are provided,and said CPU sets the number (set number) of said wireless base stationsconnectable to said extension interfaces in advance, and transmits aprogram for a wireless base station connected newly when the number ofsaid wireless base stations including said newly connected wireless basestation is within said set number.
 8. A private branch exchange systemaccording to claim 3, wherein a plurality of extension interfacesinclude said extension interface are provided; when the number of saidwireless base stations connected to said extension interfaces is one,said CPU stores a model code into said memory, said model code beingtransmitted from said wireless base station; and when a new wirelessbase station is connected to said extension interfaces, said newwireless base station is operated as long as a model code of said newwireless base station is identical to said model code stored in saidmemory.
 9. A private branch exchange system comprising: an extensioninterface capable of communicating with an extension telephone or awireless base station; a time division switch forconnecting/disconnecting channels; a memory for storing settinginformation and/or a program; a clock generator for generating a syncsignal for said wireless base station; and a CPU for controlling saidprivate branch exchange as a whole; wherein said extension interfaceincludes a feeder for feeding predetermined power to said extensiontelephone or said wireless base station, and a detector for detectingthe kind of said extension telephone or said wireless base station; saiddetector detects said wireless base station based on a response receivedby said extension interface within a predetermined feeding period afterpower is supplied from said feeder; when said detector detects saidwireless base station, said extension interface communicates with saidwireless base station, and said detector detects the kind of saidwireless base station based on a response of said wireless base stationto an enquiry transmitted by said extension interface; and said CPUdesignates a time slot of said sync signal to be supplied from saidclock generator to said extension interface through said time divisionswitch as said time slot corresponding to the kind of said wireless basestation for said extension interface based on a result of detection ofsaid detector.
 10. A private branch exchange system according to claim9, wherein said CPU transmits a program for said wireless base stationcorresponding to said detected kind based on said detection of the kindof said wireless base station.
 11. A private branch exchange systemaccording to claim 9, wherein a plurality of extension interfacesincluding said extension interface are provided, and said CPU sets thenumber (set number) of said wireless base stations connectable to saidextension interfaces in advance so as not to set a number of saidwireless base stations beyond said set number.
 12. A private branchexchange system according to claim 9, wherein a plurality of extensioninterfaces including said extension interface are provided, and said CPUsets the number (set number) of said wireless base stations connectableto said extension interfaces in advance, and transmits a program for awireless base station connected newly when the number of said wirelessbase stations including said newly connected wireless base station iswithin said set number.
 13. A private branch exchange system accordingto claim 9, wherein a plurality of extension interfaces include saidextension interface are provided; when the number of said wireless basestations connected to said extension interfaces is one, said CPU storesa model code into said memory, said model code being transmitted fromsaid wireless base station; and when a new wireless base station isconnected to said extension interfaces, said new wireless base stationis operated as long as a model code of said new wireless base station isidentical to said model code stored in said memory.
 14. A private branchexchange system according to claim 9, wherein said CPU transmitsparameter information to said wireless base station connected newly. 15.A private branch exchange system according to claim 10, wherein said CPUtransmits parameter information to said wireless base station connectednewly.
 16. A private branch exchange system according to claim 12,wherein said CPU transmits parameter information to said wireless basestation connected newly.
 17. A private branch exchange system accordingto claim 13, wherein said CPU transmits parameter information to saidwireless base station connected newly.
 18. A private branch exchangesystem according to claim 9, wherein said wireless base stationtransmits an ID code to said extension interface in addition to saidmodel code, said ID code serving to identify said wireless base stationitself.
 19. A private branch exchange system according to claim 9,wherein said wireless base station includes an indicator for indicatingrestriction of connection when connection of said wireless base stationis not permitted by said private branch exchange.